SAN FRANCISCO, April 18 — A Chinese political prisoner and his wife sued Yahoo in federal court Wednesday, accusing the company of abetting the commission of torture by helping Chinese authorities identify political dissidents who were later beaten and imprisoned.

The suit, filed under the Alien Tort Claims Act and the Torture Victims Protection Act, is believed to be the first of its kind against an Internet company for its activities in China.

Wang Xiaoning, who according to the suit is serving a 10-year prison sentence in China; his wife, Yu Ling; and other unnamed defendants seek damages and an injunction barring Yahoo from identifying dissidents to Chinese authorities.

“I hope to be able to have Yahoo promise that in the future they will stop this kind of wrongdoing,” said Ms. Yu, speaking through an interpreter in a telephone interview from San Francisco.

“Companies doing business in China are forced to comply with Chinese law,” said Jim Cullinan, a Yahoo spokesman. When government officials present the company with a lawful request for information about a Yahoo user, he said, “Yahoo China will not know whether the demand for information is for a legitimate criminal investigation or is going to be used to prosecute political dissidents.”

Several American Internet companies, including Cisco Systems, Google and Microsoft, have come under fire, with some politicians and human rights groups accusing them of helping the government monitor and censor the Internet in China.

But Yahoo has come under particularly sharp criticism. Human rights groups say that Yahoo has helped identify at least four people, including the journalist Shi Tao in 2004, who have since been imprisoned for voicing dissent in cyberspace.

“Our concern is that Yahoo, as far as we know, is continuing this practice,” said Morton Sklar, executive director of the World Organization for Human Rights USA and a lawyer for the plaintiffs.

According to the suit, Mr. Wang distributed online several journal articles calling for democratic reform and a multiparty system in China. He did so anonymously by posting the articles in a Yahoo Group in 2000 and 2001. The suit contends that Yahoo HK, a wholly owned Yahoo subsidiary based in Hong Kong, provided police with information linking Mr. Wang to the postings.

Mr. Cullinan of Yahoo disputed those claims. “Yahoo HK does not exchange info with Yahoo China or give information to mainland Chinese security forces,” he said. Yahoo transferred its mainland China operations to Alibaba.com in 2005, and owns a minority stake in that company, which is based in China.

An error has occurred. Please try again later.

You are already subscribed to this email.

On Sept. 1, 2002, Mr. Wang was arrested by Chinese authorities, according to the suit, which says he was later kicked and beaten and was detained until September 2003, when he was sentenced to 10 years.

The suit says that the Chinese court’s judgment noted that Yahoo HK told investigators that the e-mail account used to disseminate the postings belonged to Mr. Wang.

The Alien Tort Claims Act, enacted in 1789, lets foreigners sue in American courts for fundamental violations of international law, like torture and genocide. It has been used in recent years to sue people who have violated basic human rights.

Allen S. Weiner, a professor of international law at Stanford, said it was unclear whether the law would apply to a company like Yahoo, which is only accused of having contributed indirectly to Mr. Wang’s predicament. Further, Professor Weiner said that Yahoo might be excused by courts by virtue of its obligation to comply with Chinese law.

The Torture Victims Protection Act, which was enacted in 1991, allows plaintiffs, including foreign citizens, to file civil suits in the United States. Under either law, the plaintiffs would have to prove that Mr. Wang was subject to torture, Professor Weiner said.

“The plaintiffs in this case have a lot of barriers to overcome,” he said.

Suit Against Google Stands

SAN FRANCISCO, April 18 (Reuters) — A federal judge refused on Wednesday to dismiss a lawsuit contending that Google’s AdWords program abuses trademarks.

Judge Jeremy D. Fogel ruled that the public had an interest in whether AdWords, the company’s popular pay-per-click advertising system, violated trademark law.

American Blind and Wallpaper Factory, the top American retailer of window blinds, charged that Google had abused trademarks by allowing rivals of a company to buy ads that appear when users search the Web for information on its business.

A version of this article appears in print on , on Page C4 of the New York edition with the headline: Chinese Political Prisoner Sues in U.S. Court, Saying Yahoo Helped Identify Dissidents. Order Reprints|Today's Paper|Subscribe